Katy is a thirty-year-old copywriter residing in California who is entirely devastated by the recent loss of her mother. Feeling detached from her routine and uncertain about her marriage, she decides to take a pre-planned trip to Positano alone. In Italy, she encounters a magical reality where she meets a younger version of her mother, allowing her the physical and emotional distance to explore her own identity.

Carol is Katy's mother and the primary focus of Katy's grief. In California, she was a dedicated wife and a pillar of her community who managed the domestic sphere flawlessly. In Italy, she appears as an ambitious, carefree thirty-year-old woman pursuing her dream of becoming an interior designer during a summer of freedom.

Adam is a confident American developer working for the Dorchester hotel chain. He travels frequently for his job and visits Positano annually, this time with a proposal to purchase the Hotel Poseidon. Living a nomadic lifestyle, he avoids deep emotional attachments due to a tragic loss in his past.

Eric is a journalist who met Katy during their college years. He represents stability and predictability, having supported Katy through their early adulthood and her mother's illness. Despite his devotion, he is currently dealing with Katy's request for space as she takes her trip to Italy alone.

Chuck is Katy's father and the owner of a clothing design business. He worshipped his wife and relied on her entirely to manage their household and maintain order in his daily life. Following her death, he is lost in his grief and highly dependent on Katy to piece together his schedule.

Marco is the proud, traditional owner of the Hotel Poseidon in Positano. He views the family business as being as important as a child and strongly resists selling it to corporate developers, despite financial struggles.

Nika is Marco's daughter, involved in the operations of the Hotel Poseidon. Unlike her father, she takes a pragmatic view of the hotel's future and believes that accepting a corporate buyout is the best way to save their livelihood.

Remo is a local man from Naples who spends his summers working in Positano. He serves as a friendly, local guide for the young Carol, introducing her to the best spots in the city and accompanying her on boat trips and dancing outings.

Antonio is a local boat driver in Positano who transports guests to various restaurants and landmarks along the Amalfi Coast.

Amelio is a boat captain who takes Adam and Katy on a private excursion to Capri, steering them past the famous Faraglioni rock formation.

Tony is a waiter at the Hotel Poseidon restaurant who attends to Katy during her first solo meal in Italy.

Andrea is Katy's best friend from California. Their friendship has faded over time as Katy isolated herself within her marriage and her mother's illness.

Bianca is Adam's deceased sister. Her death deeply affected her family and shaped Adam's avoidance of long-term emotional commitments.